1. Введение
Enteric coated tablets have become a staple in modern pharmaceutical formulations, especially for medications that must bypass the acidic environment of the stomach. In order to produce enteric coating tablets, the pharmaceutical equipment, particularly tablet coating machines, play a crucial role. In this guide, we’ll explore what enteric coated tablets are, how they work, the types of coating methods in pharmaceutical industry, and what machinery is needed to produce them.
2. What is Enteric Coating?
Enteric coating is a protective layer applied to tablets, капсулы, or caplets that prevents them from dissolving in the acidic environment of the stomach. Instead, this coating ensures that the medication passes through the stomach intact and only dissolves in the more neutral or alkaline environment of the intestines.
Enteric coating is commonly made from pH-sensitive polymers that remain stable in low pH (acidic) but break down at higher pH levels (typically above pH 5.5 к 7.0), which are found in the small intestine. Enteric coatings are especially useful for:
• Protecting acid-sensitive active ingredients
• Preventing stomach irritation caused by certain medications
• Targeting drug release to the intestines for better absorption or therapeutic effect
3. How Do Enteric Coated Tablets Work?
Enteric coated tablets work by using a specialized outer layer that resists the acidic pH of the stomach but dissolves in the more neutral or alkaline pH of the intestines. Here’s how the process works step-by-step:
- Ingestion: Once the tablet is swallowed, it travels through the esophagus into the stomach.
- Acid Resistance: The enteric coating remains intact in the stomach (pH 1.0–3.5), protecting the active ingredients from being released or degraded by stomach acid.
- Transit to Intestines: The tablet moves into the small intestine, where the pH gradually rises to around 6.5–7.5.
- Coating Dissolution: The enteric coating is designed to dissolve at this higher pH, allowing the tablet to break apart and release its active pharmaceutical ingredient (API).
- Targeted Absorption: The drug is then absorbed in the intestine, either for localized treatment (например, anti-inflammatory drugs for bowel conditions) or for systemic circulation.
(Photo credit: https://www.pharmapproach.com/enteric-coating-2/)
4. Examples of Enteric Coated Drugs & Medicines
Enteric coated tablets are widely used in both prescription and over-the-counter (OTC) medications. In the pharmaceutical and nutraceutical industries, enteric coating is applied to a variety of dosage forms, including enteric-coated tablets and enteric coated caplets. Each form offers different benefits depending on formulation goals, drug type, and manufacturing preferences.
Common Enteric Coated Drugs
Here below are some enteric coated tablets examples for the commonly used enteric coated drugs for different category and different reasons.
Drug Name | Category | Why Use Enteric Coating |
Omeprazole
| Proton pump inhibitor | Protects acid-sensitive drug; enhances absorption in intestines |
Aspirin (Ecotrin)
| Anti-inflammatory/NSAID | Reduces gastric irritation; used for heart health |
Diclofenac Sodium
| Pain relief/NSAID | Delays release to prevent gastric ulcers |
Probiotics | Gut health supplement | Enteric coated probiotics protect live cultures through stomach acid |
Pancrelipase | Digestive enzyme therapy | Releases enzymes in the duodenum for digestion |
Divalproex Sodium
| Anticonvulsant | Reduces gastrointestinal side effects; delayed release |
(Photo credits: https://www.drugs.com/)
Enteric coated pills also come in various forms such as tablets or caplets. Here a table for the comparison for these two forms of enteric coating medicines.
Feature | Enteric Coated Tablets | Enteric Coated Caplets |
Форма | Round or oval | Oblong, streamlined |
Swallowing Ease | Умеренный | Easier than tablets |
Coating Application | Applied via film or pan coating machines | Same as tablets |
Dissolution Location | Intestine (pH-triggered) | Intestine |
Typical Use | Prescription drugs, добавки | Multivitamins, OTC medications |
Manufacturing Preference | Экономически эффективным, high volume | Easy handling, less dust |
5. Pros and Cons of Enteric Coated Tablet
Enteric coated tablets are widely used in the pharmaceutical industry for their ability to deliver active ingredients safely and effectively. Однако, while they предоставлять significant advantages, they also come with certain production and formulation challenges.
1) Advantages of Enteric Coated Таблетки
- Protection from Stomach Acid
Enteric coating is designed to remain intact in the stomach’s acidic environment and only dissolve when they reach the higher pH of the small intestine. This is ideal for drugs that can be deactivated or irritated by stomach acid. - Improved Patient Comfort
Medications like NSAIDs can irritate the stomach lining. An enteric coating helps reduce gastrointestinal side effects, improving patient adherence. - Targeted Drug Release
These coatings enable site-specific drug delivery, which is crucial for drugs that act locally in the intestines or need delayed release for therapeutic reasons. - Taste Masking
Some APIs have a bitter or unpleasant taste. Enteric coatings can help mask the taste by preventing dissolution in the mouth or stomach.
2) Disadvantages of Enteric Coated Tablets
- Complex Manufacturing Process
Applyingenteric coatings requires precise control of coating materials, temperature, spray rates, and drying parameters, often needing specialized tablet coating machines. - Longer Production Time
Compared to film-coated tablets, enteric coated drugs generally take longer to produce due to multiple layering steps and controlled drying cycles. - Risk of Incomplete Coating
If the coating process is inconsistent or the machine settings are off, the tablet may partially dissolve in the stomach, defeating its purpose. - Storage Sensitivity
Some enteric polymers are sensitive to humidity and temperature, which requires careful packaging and storage conditions to maintain coating integrity.
6. Enteric Coating vs Film Coating vs Sugar Coating: What’s the Difference?
In pharmaceutical tablet production there are three major tablet coating methods which are enteric, film, and sugar coating, so what’s their differences?
1) Definition & Application Differences
- Enteric Coating is a pH-sensitive coating that allows tablets to bypass the stomach and dissolve in the intestines. It’s commonly used for acid-sensitive drugs or to reduce gastric irritation.
- Film Coating is a thin, polymer-based layer applied to tablets for protection against moisture, to mask taste, or improve appearance. It’s widely used across pharmaceuticals and supplements for its efficiency.
- Sugar Coating is a traditional method using sugar-based layers to create a smooth, glossy finish. It improves taste and appearance but takes longer to produce and adds significant tablet weight.
2) Enteric vs Film vs Sugar Coating: Key Differences
Feature | Enteric Coating | Film Coating | Sugar Coating |
Release Site | Intestine | Stomach or modified release | Stomach |
Coating Thickness | Середина | Thin | Thick |
Taste Masking | Умеренный | Хороший | Отличный |
Скорость производства | Умеренный | Fast | Slow |
Moisture Protection | Высокий | Высокий | Низкий |
Visual Appearance | Functional | Colored or transparent | Glossy, decorative |
Вариант использования | Delayed release, acid protection | Standard tablets & branding | Chewables, pediatric, herbal |
3) Enteric vs Film vs Sugar Coating: Equipment and Coating Process
All three coatings rely on tablet coating machines, but the parameters and duration differ greatly:
- Enteric Coating Process
Requires precise control of pH-sensitive polymer spraying, drying temperature, and multiple coating stages. Typically uses perforated coating pans or fluid bed coaters. - Film Coating Process
Faster and more efficient. Tablets are sprayed with a polymer solution and dried in a coating pan under controlled airflow and temperature. - Sugar Coating Process
A time-consuming method involving multiple layering of syrup, colors, and sealants using traditional coating pans. Can take hours to complete.
7. Key Pharmaceutical Equipment for Tablet Coating
Enteric coating requires pharmaceutical equipment such as automatic tablet coating machines ensures that this enteric layer is applied uniformly and effectively, which is key to the tablet’s functionality and patient safety. Below are the core types of pharmaceutical equipment used in tablet coating, especially in industrial-scale production.
1) Automatic Tablet Coating Machines
Automatic tablet coating machines are the backbone of large-scale pharmaceutical production. They use advanced spray systems, programmable controls, and temperature management to apply uniform coatings efficiently. These machines significantly reduce coating variability, minimize product waste, and improve operational throughput, making them ideal for mass production of enteric-coated and film-coated tablets.
Recommended Automatic Tablet Coating Machine: RD-BG-80
(Photo credit: www.ruidapacking.com)
Comparing to the other models of the automatic tablet coating machine, this models has the major advantages and features as below:
- Iwata Spray System, Precision and Consistency: Many coating machines on the market use basic spray nozzles, but the RD-BY-80 uses high-end Iwata nozzles, known for fine atomization and consistent coverage, reducing coating material waste and rework.
- Versatility for Multiple Coating Types: Some models are optimized only for film coating or sugar coating, but this one handles film, сахар, and enteric coatings equally well, providing flexibility for different product lines.
- Advanced Drying Efficiency: The use of a perforated drum with integrated hot air system ensures faster and more uniform drying than standard smooth pans, which reduces processing time and improves coating quality.
2) Perforated Pan Coaters
Perforated pan coaters are widely used for film coating, sugar coating, and enteric coating. Tablets are loaded into a perforated drum that rotates while hot air is circulated through the perforations. The coating solution is sprayed onto the tumbling tablets, and the warm air quickly dries each layer. This method ensures even coverage and maintains tablet integrity throughout the process.
(Photo credit: www.richpacking020.com)
3) Fluid Bed Coaters
Fluid bed coaters are specialized for coating small tablets, гранулы, or pellets. In this system, particles are suspended in an upward flow of air while the coating material is atomized and sprayed from below. This technique provides excellent coating uniformity and is especially useful for products requiring multiple layers or functional coatings like delayed release or sustained release.
8. FAQ/Common Issues
Manufacturers and formulation teams often encounter key challenges and recurring questions when working with enteric coated tablets. Below are the most frequently asked questions and issues from a B2B perspective, along with solutions and expert tips.
Q1: Why is the enteric coating peeling or cracking during production?
Peeling or cracking usually indicates issues with coating formulation or drying parameters. Improper polymer concentration, excessive mechanical stress, or insufficient drying can all contribute.
Solution:
- Optimize coating solution viscosity and solid content.
- Use a precision-controlled automatic tablet coating machine with hot air systems.
- Avoid overloading the drum and minimize tablet attrition.
вопрос2: How to ensure consistent coating thickness across all tablets?
Inconsistent coating can lead to premature dissolution or delayed release failures.
Solution:
- Use automated spray guns and real-time monitoring systems on coating machines.
- Ensure uniform tablet size and shape via a rotary tablet press with tight tolerances.
Q3: How to avoid cross-contamination during enteric coating production?
Cross-contamination is a regulatory red flag, especially in multi-product facilities.
Solution:
- Use equipment with quick-cleaning design and segmented product paths.
- Implement SOPs (Standard Operating Procedures)for line clearance and verify with swab tests.
Q4: Can enteric coating machines handle multiple types of coatings (film, сахар, etc.)?
Да, but only if the machine supports programmable coating profiles and interchangeable spray nozzles.
Solution:
- Choose a versatile tablet coater with multi-process capabilities.
- Work with pharmaceutical equipment manufacturers that provide tablet coating solution consultation and training.
9. Заключение
Enteric coated tablets offer targeted drug delivery and protect sensitive ingredients from stomach acid. They are essential for many modern formulations. For pharmaceutical product manufacturers, understanding coating types and choosing the right pharmaceutical equipment like tablet coating machines, is key to ensuring product quality and compliance. With the right equipment and knowledge, producing high-performance enteric coated tablets becomes efficient and reliable.
